at the top on spear pillar you will need surf strength and roch climb
If you're playing Diamond, the Pokemon in Mt. Coronet should be Dialga. You have to get the 7th badge before you are able to get to the top of Mt. Coronet where Dialga is though.
atop mt coronet is dialga in diamond, palkia in pearl, or both and giratina in platinum.
that's where you catch dialga or palkia
Spear Pillar, which is at the very top.
go to mt coronet to catch palkia or dialga
you go and battle dialga
If you keep going through Mt Coronet you'll eventually reach Spear Pillar, where you catch Dialga, Palkia and Arceus. You can't fly from Spear Pillar, though.
You catch dialga/palkia on spear pillar inside of Mt. Coronet for diamond or pearl
Dialga is at the top of Mnt Coronet.(Go from Heartrome city side!)
North in Mt Coronet and u get to spear pillar -lassi97-
Dialga in Pokemon diamond, and in platinum Palkia.
Mt. Coronet right behind giratina